1. Field of the Invention
This invention relates to polymeric delivery systems, and, more particularly, to a non-continuous, aqueous vinyl lactam polymeric composition having two phases therein, particularly suitable for delivering a water-insoluble active material dispersed therein.
2. Description of the Prior Art
Polymeric compositions of vinyl lactam monomers generally are one-phase, soluble, high viscosity materials. These compositions are found in a variety of commercial applications such as film formers, dye transfer inhibitors, rheology modifiers, dispersants, excipients, and drug delivery. Aqueous gels of these monomers can also be prepared by light covalent or associative crosslinking of polymer chains resulting in a highly swellable, one phase material of high viscosity. Such compositions are effective thickeners for use in personal care formulations such as hair care products.
The following prior art is representative of this technology.
Niessner, in U.S. Pat. Nos. 5,149,750 and 5,180,804, disclosed finely divided, water-swellable gel-like, water-swellable copolymers by polymerization of comonomers in the presence of a surfactant.
Liu, in U.S. Pat. No. 5,997,855, described a homogeneous terpolymer for hair care use, however, without a crosslinking agent.
Kopolow, in U.S. Pat. No. 5,130,121, described personal care compositions containing a stabilized cosmetically-active product obtained by in situ polymerization of a water-soluble vinyl monomer in the presence of discrete microdroplets of a cosmetically-active oil in water.
Blankenburg, in U.S. Pat. Nos. 5,635,169 and 6,107,397, described uncrosslinked aqueous copolymer dispersions of nonionic water-soluble monomers with N-vinyl groups, and hydrophobic monomers.
Steckler, in U.S. Pat. No. 3,878,175, disclosed highly absorbent spongy gel polymer materials by simultaneously copolymerizing and partially crosslinking a comonomer mixture of an alkyl acrylate and a heterocyclic N-vinyl monomer containing a carbonyl functionality in the presence of a hydrophobic liquid diluent in which the final polymer is insoluble.
Markus, in U.S. Pat. No. 2,810,716, described a process for making swellable resins by copolymerizing suitable monomers in the presence of a water-soluble non-redox divalent-ion containing salt.
Tseng, in U.S. Pat. Nos. 5,393,854 and 5,717,045, disclosed a one-phase, aqueous gel of crosslinked copolymers of vinyl pyrrolidone and dimethylaminoethyl methacrylate for use in hair care products. The crosslinking agent was 1-vinyl-3-(E)-ethylidene pyrrolidone. The gels had a Brookfield viscosity of between 60,000 and 100,000.
These references illustrate the desire of the art to produce a continuous network of polymer molecules, or microgel, which is a one-phase system, and of high viscosity.
Accordingly, it is an object of the present invention to provide a polymeric system capable of delivering an active material dispersed therein, which includes an aqueous polymeric composition which is not a gel but a combination of a film-forming polymer and substantially uniformly dispersed minute resinous particles, that, under suitable light magnification, shows the presence of two discrete phases therein, one phase including a water soluble polymer and the other phase constituting in situ-formed, water-insoluble resinous particles, and including an active material uniformly dispersed in said composition.
Another object of the invention is to provide an aqueous polymeric system for delivering active materials ordinarily present in personal care formulations, such as silicones, fragrances, sunscreens, and the like; in nutrient, medicament and pharmaceutical formulations, such as drugs, for example, aspirin, and syrups and the like.
These and other objects and features of the invention will be made apparent from the following description.